Digital audio broadcasting method using puncturable convolutional code

Abstract

A broadcasting method comprising the steps of encoding program material using codes including a first set of bits and a second set of bits, the first set of bits contributing a greater coding gain to the codes than the second set of bits, modulating a plurality of orthogonal frequency division multiplexed carrier signals with the codes, whereby the first set of bits are carried by a first group of the carrier signals and the second set of bits are carried by a second group of the carrier signals, the first group of carrier signals being less susceptible to interference than the second group of carrier signals, broadcasting the carrier signals, receiving the carrier signals, estimating the interference to which the carrier signals in the second group have been subjected to determine if carrier signals in the second group have been corrupted, erasing bits carried by any of the carrier signals which have been determined to be corrupted, and decoding bits of the codes that have not been erased.

What is claimed is:  
     
       1. A broadcasting method comprising the steps of: 
       encoding program material using codes including a first set of bits and a second set of bits, said first set of bits contributing a greater coding gain to said codes than said second set of bits;  
       modulating a plurality of orthogonal frequency division multiplexed carrier signals with said codes, whereby said first set of bits are carried by a first group of said carrier signals and said second set of bits are carried by a second group of carrier signals, said first group of carrier signals being less susceptible to interference than said second group of carrier signals;  
       broadcasting said carrier signals;  
       receiving said carrier signals;  
       estimating the interference to which the carrier signals in said second group of carrier signals have been subjected to determine if carrier signals in said second group have been corrupted;  
       erasing bits carried by any of said carrier signals which have been determined to be corrupted; and  
       decoding bits of said codes that have not been erased.  
     
     
       2. A broadcasting method comprising the steps of: 
       encoding program material using codes including a first set of bits and a second set of bits, said first set of bits contributing a greater coding gain to said codes than said second set of bits;  
       modulating a plurality of orthogonal frequency division multiplexed carrier signals with said codes, whereby said first set of bits are carried by a first group of said carrier signals and said second set of bits are carried by a second group of carrier signals, said first group of carrier signals being less susceptible to interference than said second group of carrier signals;  
       broadcasting said carrier signals;  
       said plurality of orthogonal frequency division multiplexed carrier signals are positioned in upper and lower sidebands of a radio channel; and  
       said codes comprise first and second complementary codes, said first complementary code being used to modulate said orthogonal frequency division multiplexed carrier signals in said upper sideband and said second complementary code being used to modulate said orthogonal frequency division multiplexed carrier signals in said lower sideband.  
     
     
       3. The method of  claim 2 , wherein said first and second complementary codes comprise puncturable convolutional codes. 
     
     
       4. The method of  claim 2 , wherein said second set of bits contains audio information and said first set of bits contains data. 
     
     
       5. The method of  claim 2 , wherein said codes are rate compatible convolutional codes. 
     
     
       6. The method of  claim 2 , wherein said codes are systematic convolutional codes. 
     
     
       7. A broadcasting method comprising the steps of: 
       encoding program material using codes including a first set of bits and a second set of bits, said first set of bits contributing a greater coding gain to said codes than said second set of bits;  
       modulating a plurality of orthogonal frequency division multiplexed carrier signals with said codes, whereby said first set of bits are carried by a first group of said carrier signals and said second set of bits are carried by a second group of carrier signals, said first group of carrier signals being less susceptible to interference than said second group of carrier signals;  
       broadcasting said carrier signals; and  
       interleaving said codes among said carrier signals.  
     
     
       8. The method of  claim 7 , wherein said interleaving step comprises the step of: 
       partitioning said codes to produce partitioned codes; and  
       mapping said partitioned codes to predetermined ones of said carrier signals.  
     
     
       9. The method of  claim 8 , the step of mapping said partitioned codes to predetermined ones of said carrier signals assigns bits of said second set of bits to carrier signals in said second group of carrier signals. 
     
     
       10. A broadcasting method comprising the steps of: 
       encoding program material using codes including a first set of bits and a second set of bits, said first set of bits contributing a greater coding gain to said codes than said second set of bits;  
       modulating a plurality of orthogonal frequency division multiplexed carrier signals with said codes, whereby said first set of bits are carried by a first group of said carrier signals and said second set of bits are carried by a second group of carrier signals, said first group of carrier signals being less susceptible to interference than said second group of carrier signals; and  
       broadcasting said carrier signals;  
       wherein said carrier signals lie in a channel and the second group of carrier signals are positioned at frequencies farther from a center channel frequency than said first group of carrier signals.  
     
     
       11. A broadcasting method comprising the steps of: 
       encoding program material using codes including a first set of bits and a second set of bits, said first set of bits contributing a greater coding gain to said codes than said second set of bits;  
       modulating a plurality of orthogonal frequency division multiplexed carrier signals with said codes, whereby said first set of bits are carried by a first group of said carrier signals and said second set of bits are carried by a second group of carrier signals, said first group of carrier signals being less susceptible to interference than said second group of carrier signals;  
       broadcasting said carrier signals;  
       receiving said plurality of orthogonal frequency division multiplexed carrier signals;  
       determining if carrier signals in said second group have been corrupted;  
       weighting bits carried by any of said carrier signals which have been determined to be corrupted to produce weighted codes; and  
       decoding said weighted codes.  
     
     
       12. The method of  claim 11 , wherein said step of determining if carrier signals in said second group have been corrupted comprises the step of: 
       determining a signal to noise ratio for said carrier signals; and  
       wherein the step of weighting bits carried by any of said carrier signals which have been determined to be corrupted to produce weighted codes comprises the steps of:  
       weighting said bits in response to said signal to noise ratio.  
     
     
       13. A method for receiving a radio frequency signal comprising the steps of: 
       receiving a plurality of orthogonal frequency division multiplexed carrier signals with codes including a first set of bits and a second set of bits, said first set of bits contributing a greater coding gain to said codes than said second set of bits, wherein said first set of bits are carried by a first group of said carrier signals and said second set of bits are carried by a second group of said carrier signals, said first group of said carrier signals being less susceptible to interference than said second group of said carrier signals;  
       determining if carrier signals in said second group have been corrupted by estimating the interference to which the carrier signals in said second group of carrier signals have been subjected;  
       erasing bits carried by any of said carrier signals which have been determined to be corrupted; and  
       decoding bits of said codes that have not been erased.  
     
     
       14. A method for receiving a radio frequency signal comprising the steps of: 
       receiving a plurality of orthogonal frequency division multiplexed carrier signals with codes including a first set of bits and a second set of bits, said first set of bits contributing a greater coding gain to said codes than said second set of bits, wherein said first set of bits are carried by a first group of said carrier signals and said second set of bits are carried by a second group of said carrier signals, said first group of said carrier signals being less susceptible to interference than said second group of said carrier signals;  
       determining if carrier signals in said second group have been corrupted based on a signal to noise ratio for said carrier signals;  
       weighting bits carried by any of said carrier signals which have been determined to be corrupted to produce weighted codes in response to said signal to noise ratio; and  
       decoding said weighted codes.  
     
     
       15. A radio frequency transmitter comprising: 
       means for encoding program material using codes including a first set of bits and a second set of bits, said first set of bits contributing a greater coding gain to said codes than said second set of bits;  
       means for modulating a plurality of orthogonal frequency division multiplexed carrier signals with said codes, whereby said first set of bits are carried by a first group of said carrier signals and said second set of bits are carried by a second group of carrier signals, said first group of carrier signals being less susceptible to interference than said second group of carrier signals;  
       means for broadcasting said carrier signals;  
       means for interleaving said codes into partitions to produce partitioned codes; and  
       means for mapping said partitioned codes to said plurality of orthogonal frequency division multiplexed carrier signals.  
     
     
       16. A radio frequency transmitter comprising: 
       an encoder for encoding program material using codes including a first set of bits and a second set of bits, said first set of bits contributing a greater coding gain to said codes than said second set of bits;  
       a modulator for modulating a plurality of orthogonal frequency division multiplexed carrier signals with said codes, whereby said first set of bits are carried by a first group of said carrier signals and said second set of bits are carried by a second group of carrier signals, said first group of carrier signals being less susceptible to interference than said second group of carrier signals;  
       an interleaver for interleaving said codes into partitions to produce partitioned codes, and for mapping said partitioned codes to said plurality of orthogonal frequency division multiplexed carrier signals; and  
       an antenna for broadcasting said carrier signals.  
     
     
       17. A radio frequency receiver comprising: 
       means for receiving a plurality of orthogonal frequency division multiplexed carrier signals with codes containing a first set of bits and a second set of bits, said first set of bits contributing a greater coding gain to said codes than said second set of bits, wherein said first set of bits are carried by a first group of said carrier signals and said second set of bits are carried by a second group of carrier signals, said first group of carrier signals being less susceptible to interference than said second group of said carrier signals;  
       means for determining if carrier signals in said second group of said carrier signals have been corrupted based on a signal to noise ratio for said carrier signals;  
       means for erasing bits carried by any of said carrier signals which have been determined to be corrupted; and  
       means for decoding bits of said codes that have not been erased.  
     
     
       18. A radio frequency receiver comprising: 
       an antenna for receiving a plurality of orthogonal frequency division multiplexed carrier signals with codes containing a first set of bits and a second set of bits, said first set of bits contributing a greater coding gain to said codes than said second set of bits, wherein said first set of bits are carried by a first group of said carrier signals and said second set of bits are carried by a second group of carrier signals, said first group of carrier signals being less susceptible to interference than said second group of said carrier signals;  
       an editor for determining if carrier signals in said second group of said carrier signals have been corrupted based on a signal to noise ratio for said carrier signals, and for erasing bits carried by any of said carrier signals which have been determined to be corrupted; and  
       a decoder for decoding bits of said codes that have not been erased.  
     
     
       19. A radio frequency receiver comprising: 
       means for receiving a plurality of orthogonal frequency division multiplexed carrier signals with codes containing a first set of bits and a second set of bits, said first set of bits contributing a greater coding gain to said codes than said second set of bits, wherein said first set of bits are carried by a first group of said carrier signals and said second set of bits are carried by a second group of carrier signals, said first group of carrier signals being less susceptible to interference than said second group of said carrier signals;  
       means for determining if carrier signals in said second group have been corrupted based on a signal to noise ratio for said carrier signals;  
       means for weighting bits carried by any of said carrier signals which have been determined to be corrupted to produce weighted codes; and  
       means for decoding said weighted codes.  
     
     
       20. A radio frequency receiver comprising: 
       an antenna for receiving a plurality of orthogonal frequency division multiplexed carrier signals with codes containing a first set of bits and a second set of bits, said first set of bits contributing a greater coding gain to said codes than said second set of bits, wherein said first set of bits are carried by a first group of said carrier signals and said second set of bits are carried by a second group of carrier signals, said first group of carrier signals being less susceptible to interference than said second group of said carrier signals;  
       an editor for determining if carrier signals in said second group have been corrupted based on a signal to noise ratio for said carrier signals, and for weighting bits carried by any of said carrier signals which have been determined to be corrupted to produce weighted codes; and  
       a decoder for decoding said weighted codes.  
     
     
       21. A radio frequency broadcasting system comprising: 
       a transmitter including means for encoding program material using codes including a first set of bits and a second set of bits, said first set of bits contributing a greater coding gain to said codes than said second set of bits; means for modulating a plurality of orthogonal frequency division multiplexed carrier signals with said codes, whereby said first set of bits are carried by a first group of said carrier signals and said second set of bits are carried by a second group of carrier signals, said first group of carrier signals being less susceptible to interference than said second group of carrier signals; and means for broadcasting said carrier signals;  
       a receiver including means for receiving a plurality of orthogonal frequency division multiplexed carrier signals with codes containing a first set of bits and a second set of bits, said first set of bits contributing a greater coding gain to said codes than said second set of bits, wherein said first set of bits are carried by a first group of said carrier signals and said second set of bits are carried by a second group of carrier signals, said first group of carrier signals being less susceptible to interference than said second group of said carrier signals; means for determining if carrier signals in said second group of said carrier signals have been corrupted; means for erasing bits carried by any of said carrier signals which have been determined to be corrupted; and means for decoding bits of said codes that have not been erased;  
       means for interleaving said codes into partitions to produce partitioned codes; and  
       means for mapping said partitioned codes to said plurality of orthogonal frequency division multiplexed carrier signals.  
     
     
       22. A radio frequency broadcasting system comprising: 
       a transmitter including an encoder for encoding program material using codes including a first set of bits and a second set of bits, said first set of bits contributing a greater coding gain to said codes than said second set of bits; a modulator for modulating a plurality of orthogonal frequency division multiplexed carrier signals with said codes, whereby said first set of bits are carried by a first group of said carrier signals and said second set of bits are carried by a second group of carrier signals, said first group of carrier signals being less susceptible to interference than said second group of carrier signals; and an antenna for broadcasting said carrier signals;  
       a receiver including an antenna for receiving a plurality of orthogonal frequency division multiplexed carrier signals with codes containing a first set of bits and a second set of bits, said first set of bits contributing a greater coding gain to said codes than said second set of bits, wherein said first set of bits are carried by a first group of said carrier signals and said second set of bits are carried by a second group of carrier signals, said first group of carrier signals being less susceptible to interference than said second group of said carrier signals; an editor for determining if carrier signals in said second group of said carrier signals have been corrupted, and for erasing bits carried by any of said carrier signals which have been determined to be corrupted; and a decoder for decoding bits of said codes that have not been erased; and  
       an interleaver for interleaving said codes into partitions to produce partitioned codes, and for mapping said partitioned codes to said plurality of orthogonal frequency division multiplexed carrier signals.  
     
     
       23. A radio frequency broadcasting system comprising: 
       a transmitter including an encoder for encoding program material using codes including a first set of bits and a second set of bits, said first set of bits contributing a greater coding gain to said codes than said second set of bits; a modulator for modulating a plurality of orthogonal frequency division multiplexed carrier signals with said codes, whereby said first set of bits are carried by a first group of said carrier signals and said second set of bits are carried by a second group of carrier signals, said first group of carrier signals being less susceptible to interference than said second group of carrier signals; and an antenna for broadcasting said carrier signals; and  
       a radio frequency receiver including an antenna for receiving a plurality of orthogonal frequency division multiplexed carrier signals with codes containing a first set of bits and a second set of bits, said first set of bits contributing a greater coding gain to said codes than said second set of bits, wherein said first set of bits are carried by a first group of said carrier signals and said second set of bits are carried by a second group of carrier signals, said first group of carrier signals being less susceptible to interference than said second group of said carrier signals; an editor for determining if carrier signals in said second group have been corrupted based on a signal to noise ratio for said carrier signals, and for weighting bits carried by any of said carrier signals which have been determined to be corrupted to produce weighted codes; and a decoder for decoding said weighted codes.